Patent Document 1 discloses a curable composition comprising a linear fluoropolyether compound containing at least two alkenyl groups in the molecule and having a perfluoropolyether structure in its backbone, a fluorinated organohydrogensiloxane having at least two silicon-bonded hydrogen atoms in the molecule, and a platinum group compound. The composition cures into a cured product having a good profile of heat resistance, chemical resistance, solvent resistance, mold release, water repellency, oil repellency, and low-temperature properties.
Patent Document 2 describes that the cured product of the above-mentioned composition is improved in acid resistance by modifying the linear fluoropolyether compound.
It is known that many electric/electronic parts such as CPUs, power transistors and LSIs lose their performance by the heat release during service. Various heat-dissipating techniques are used for removing heat from these parts. Typical examples are heat-dissipating grease and sheets of thermosetting silicone rubber compositions having heat-conductive fillers added thereto (see Patent Documents 3 to 5). Heat-conductive materials in the form of such silicone rubbers (cured products of thermosetting silicone rubber compositions) find increasing applications in the automotive field because of their heat resistance, weather resistance, and electrical insulation. For example, the heat-conductive materials are used in LED headlamps and engine control units (ECUs) as well as in batteries, motors and converters mounted on next-generation automobiles including hybrid cars and electric vehicles.
However, silicone rubbers are prone to swell or degrade by solvents such as toluene, alcohols and gasoline. When used in an environment exposed to automobile fluids such as ATF or CVTF, heat-conductive materials based on silicone rubber are difficult to maintain their performance. To address the problem, heat-conductive materials based on fluoro-rubber are recently proposed.
For instance, Patent Document 6 discloses a composition comprising a perfluoropolyether compound and a heat-conductive filler as the heat-dissipating fluorinated grease having heat transfer properties. Patent Document 7 describes that a heat-resistant heat-dissipating sheet is obtained by mixing a liquid fluorinated polyether and a heat-conductive filler and reactive curing.
Besides, Patent Document 8 describes that a heat-conductive rubber sheet is obtained by heating a composition comprising a compound having a perfluoroalkylether structure in its backbone and a hydrosilyl group at the molecular end, a compound having a perfluoroalkylether structure in its backbone and an alkenyl group at the molecular end, and a heat-conductive filler. Patent Document 9 proposes to add an electro-conductive filler to the composition of Patent Document 8, and a cured product of the resulting composition serves as a heat-conductive sheet.
The heat-conductive materials described in Patent Documents 6 to 9, however, have problems that when the amount of heat-conductive filler added to the composition is increased to improve heat conduction, the composition does not become grease because of non-uniform dispersion of the filler in the composition or has an extremely high viscosity that interferes with working or shaping.